Preorder, Back In Stock ‑ STOQ

It's a straightforward app that does exactly what I need it to do. Support was prompt, clear, and effective.
UPDATE:
I just had a session with Vishu, and he went ABOVE AND BEYOND what I expected to help me set up my pre-order. I was floored by how long he stayed on chat with me. I love this app, just by customer service alone.